Fifteen years ago, Arizona voters took a drastic step to deal with partisanship in drawing the lines for federal congressional districts: they passed an amendment to the state constitution that transferred the redistricting power from the state legislature, which had previously controlled it, to an independent commission. Perhaps it comes as no surprise that the legislature objected to being cut out of the process and filed a lawsuit, which went all the way to the U.S. Supreme Court. The legislature alleged that tasking the commission with redistricting violates the U.S. Constitution’s Elections Clause, which provides that the “Times, Places and Manner of holding Elections for . . . Representatives, shall be prescribed in each State by the Legislature thereof” – because the phrase “the Legislature” can only refer to the official body that makes laws for the state.

Yesterday the Supreme Court rejected the legislature’s argument, in a decision that will be welcomed by many not only in Arizona, where the independent redistricting commission can continue to operate, but also in other states (including California) that also use commissions for redistricting. Let’s talk about the ruling in Arizona State Legislature v. Arizona Independent Redistricting Commission in Plain English.

Justice Ruth Bader Ginsburg wrote the Court’s opinion, which was joined by Justices Anthony Kennedy, Stephen Breyer, Sonia Sotomayor, and Elena Kagan. Dictionaries in print around the time that the Constitution was drafted, the Court pointed out, defined the word “legislature” as “the power that makes laws.” And in Arizona, the power to make laws rests not only with the official body of elected representatives, but also with the voters themselves, who have the power under the state constitution to pass laws and constitutional amendments through initiatives – just as they did in this case.

Defining “legislature” in this way is, the Court reasoned, also consistent with what the Court described as “the fundamental premise that all political power flows from the people,” and “the core principle of republican government . . . that the voters should choose their representatives, not the other way around.” And as a practical matter, this interpretation (unlike the legislature’s) leaves a whole host of other voter initiatives, ranging from Ohio’s ban on straight-ticket voting along party lines to a California law establishing permanent voter registration, in place.

Last week in King v. Burwell, Chief Justice John Roberts wrote for the Court in holding that the Affordable Care Act’s reference to health-insurance exchanges “established by the State” also includes health-insurance exchanges established by the federal government. But in this case, in a dissent joined by Justices Antonin Scalia, Samuel Alito, and Clarence Thomas, he took a narrow view of the word “Legislature.” He argued that, when the Constitution was drafted, the word “Legislature” referred only to the official body of elected representatives – an understanding that is reflected in the Constitution’s many references to a state’s “Legislature.” And in particular, Roberts emphasized, the entire purpose of the Seventeenth Amendment was to allow the people in each state – rather than the state “Legislature” – to elect senators. “What chumps,” he observed sarcastically. “Didn’t they realize that all they had to do was interpret the constitutional term ‘the Legislature’ to mean ‘the people’?”

Yesterday’s decision gives voters a new tool to minimize the circumstances in which the party which controls the state legislature draws congressional district boundaries in a way most favorable to it. It will be interesting to watch in the months and years ahead to see whether voters actually opt to do so. And with the announcement of yesterday’s opinions, the Court is now in recess until the first Monday in October, when they will return and grapple with a new set of hot-button issues such as affirmative action, public-employee unions, and (in all likelihood) abortion. You can be sure that we’ll be back as well, to cover all of those cases in Plain English.